• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

The "$250" Amp? - 6LU8 Compactron SE, UL

Crap Out

sled108 said:
Alright Guys...What would cause something like this to Crap Out??
Click to expand...

Ok,

I opened mine up to see what I did to fix it.

I jumpered both positions on the switch together and tied them to the lead that I thought was for the most windings ie high power!

I did many scientific measurements of the coil and the switch first.

Pretty sure I ended up proving something was wrong with the switch, but this seemed to fix it.

If this had not fixed it I was just going to wired it always on, because, I have not used mine much at all so I felt I had not burned it out or anything.

It would have made more sense to try one or then the other, but I bet it was the half power step that is bad since you always transition through it. But I could not figure out why that would make the fully depressed position not work??

Now it works great fully depressed.

Ok, I admit it, I have no clue why this fixed it

Good luck!

Dan
 

Attachments

  • Weller(1).JPG
    Weller(1).JPG
    127.5 KB · Views: 91
I like that cake pan amp.

Reminds me of this amp in the October 1956 Radio-Electronics magazine: "The Long-Tailed Cascode-Pair Amplifier"


cakeqn9.jpg
 
Well, There is still is 1 Item that may, or may not be needed, that is the only thing so far that Granny might have Burnt me on E-Bay...But we'll See...
 
sled108 said:
Alright Guys...What would cause something like this to Crap Out??
Click to expand...

Usually you can feel the thing buzzing in your hand when you squeeze the trigger, which means it's working. If it's doing that, then either clean and re-install the tip or put in a new one. They don't last forever.
 
I finished an order to Allied, now I have to finish my RadioDaze order. I expect that to be done in the next day or two. We'll have a complete BoM then.
 
Get yourself one of these irons, best soldering iron I've ever used. I've bought and used Wellers, Radio Shack, but these Antex irons are the best. Really quick heat up time, so quick in fact, if I'm making a circuit and have to figure out component placement, I can turn the iron off so it doesn't cook. I use the 12v one simply because I do a lot of car electrics. At home, I just plug it into a 12 power supply.

http://www.maplin.co.uk/Module.aspx?ModuleNo=4067
 
Whoo hoo, Way to go Squid!

I believe many will be happy when you get the BOM posted! Good Job!
 
Well, it's working... sort of...The volume is low, and B+ is 336V....Why would that Be?
 
Last edited:
Your voltage should not be to high to hurt anything. (there is leeway in those tubes)

I would fire it up and take readings pretty much everywhere on the amp an post them.

One that helps when trouble shooting, ecspecially on a simple circuit, is don't go by the
schem you think, trace out the schem you built in the amp, in otherwords create schem
based on exactly what you built, if you made an error it should be easy to spot that way.

-----------

Nice job on the build, I like the layout and look quite a bit!
 
Thanks Kegger....It has 167V @ the 155V Point, 37V & 2.1V on both channels. Could I have made an Error by adding the 100K Alps to the Circuit?
 
What are you measuring at the first cap? I see that you are using a slightly different PS than the one we experimented with. What size is your first cap?
 
We are using a 275-0-275 PT, and we are using about a 6-10uF film cap for input. If you have a similar PT, I'd suggest using a smaller input cap to get closer to the target voltage.

As Keg said, there is a bit of leeway in what the tubes can take. The funny thing is that we even talked about this event, what happens if someone builds it and gets too high voltage? Thanks for being our first test case!
 
Thanks Squidward, I'll have to look into my Box of Tricks for a 10uf or so...I posted the PS on Page 24 Post 346.....But I still have to Chase down my lack of Volume.
 
You must log in or register to reply here.
Back
Top Bottom